A combine harvester is a machine that is used to harvest grain crops, such as wheat, oats, rye, barley, corn, soybeans, flax or linseed, and others. The waste (e.g., straw) discharged on the field includes the remaining dried stems and leaves of the crop which may be, for example, chopped and spread on the field as residue or baled for feed and bedding for livestock.
A combine harvester uses a number of combine components/systems during harvesting. A cutting system cuts the crop using a wide cutting header. The cut crop is picked up and moved from outer areas of the header toward the center area of the header using an auger or belt system and conveyed to a feeder system. The cut crop is then fed by the feeding system into the threshing and separating mechanism of the combine for separating the grains from material other than grain (MOG). The cut crop is feed through, in part, by a concave that helps guide the cut crop into and around the threshing rotor. The MOG is expelled out of the rear of the combine, while the grain, chaff, and other small debris fall through concaves and grates onto a cleaning device or shoe, where it is further separated from the chaff by way of a winnowing process. Clean grain is transported to a grain tank in the combine for temporary storage. The grain tank is typically located atop the combine and loaded via a conveyer that carries clean grain collected in the cleaning system to the grain tank. The grain may then be unloaded through a conveying system to a support trailer or vehicle, allowing large quantities of grain to be unloaded in the field without needing to stop harvesting when the grain tank fills.
Conventional concaves do not provide any substantial rearward motion to continuously feed the crop through the combine.